"Locate the Templar Admiral's ship using the spyglass" is an optional mission objective in The Calm Before The Storm in Freedom Cry
Walkthrough[edit]
As you close on the ships, use the Spyglass. There are 2 schooners, a brig and a man o' war, the Hercule. One of them is the Admiral's ship. Use the Spyglass, while still at a distance, to look at the Man o War. Mark it so you know what you are looking for.